Latching device



C. E. DALBEY April 9, 1968 LATCHING DEVICE l Filed Aug. 17. 1966 CARL E. DALBEY rOm.

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BUC/(HORN, LURE, KLPOU/ST SP/(MAN Arrow/grs United States Patent O 3,377,116 LATCHING DEVICE Carl E. Dalbey, Portland, Oreg., assignor to Tektronix, Inc., Beaverton, Oreg., a corporation of Gregori Filed Aug. 17, 1966, Ser. No. 573,029 9 Claims. (Cl. S12-333) ABSTRACT F THE DISCLOSURE A plug-in unit is slidably received within a frame and is automatically secured in engaged position therewithin by an automatic latching mechanism. The latching mechanism further includes an unlatching means connected to a handle located on an accessible front panel of the plug-in unit. When the plug-in unit is to be physically withdrawn from the frame, the handle is grasped and moved in a direction to withdraw the plugin unit. Movement of the handle brings about unlatching of the latching mechanism.

Specification The present invention relates to a latching device and particularly to such a device for preventing relative movement between two members, such device becoming automatically disengaged as one member is removed from the other.

Modern electronic equipment frequently employs a modular plug-in concept whereby one portion of an electronic apparatus may be conveniently disconnected and physically removed from another. Thus, an electronic instrument may be provided with alternative input amplifier sections that can be inserted into the main frame of the instrument and then removed and replaced as desired. This arrangement renders the instrument more versatile without affecting the compactness or mechanical and electronical rigidity of the instrument in operation.

A typical plug-in unit slides upon tracks into a main frame of electronic apparatus and this unit is provided with an electrical connector at the inserted end thereof for establishing the electrical circuit when the unit is completely inserted. To prevent accidental separation of the Iplug-in from the main frame and provide necessary rigidity, it is conventional to employ screw-thread fasteners or the like in order to secure the plug-in unit in place. In one example, a plug-in unit is provided with a plurality of `thumb screws which are turned each time a plug-in unit is inserted, and which must be completely disengaged before the plug-in unit is removed. Fasteners of this type, while insuring rigid mechanical and electrical connection, are nonetheless time consuming in manipulation.

Various conventional locks and latches are also feasible for securing a plug-in to a frame. However, devices of this type usually require additional space in the body or on the front panel of the equipment and also usually involve more than one motion in removal of the plugin unit from the frame. Thus, the latch must ordinarily be disengaged before the unit is physically withdrawn, or otherwise dama-ge will `result to the latch or to the equipment. Since more than one such latching device is usually employed, the number of operations in removing a plugin unit is accordingly multiplied.

It is accordingly an object of the present invention to provide an improved latching device which unlatches automatically when the latched members are separated by means of grasping and outwardly urging an operating handle.

It is another object of the present invention to provide an improved latching device which is operable to cause 3,3711 1s Patented Apr. 9, 1968 AICC removal of one latched member from another latched member, such device having an operating means for simultaneously performing both the unlatching function and a removal function in one motion.

It is a further object of the present invention to provide an improved latching device for automatically securing a removable plug-in unit in a receiving frame wherein the latching device is automatically released when the plug-in unit is withdrawn.

It is another object of the present invention to provide an improved latching device having an outwardly extending operating member in common Vwith the means employed for removing one latched member from another.

In accordance with broader aspects of the present invention, a yunit member is slidably receivable in a main frame member. These members are provided with latching means mounted on one of the members and yieldably urged towards the other of the members for engaging a latching surface to provide an interlocking engagement when the unit member is inserted in the frame member. An unlatching means is mounted on the unit member and is engageable with the latching means for forcing the same out of engagement. This unlatching means is provided with an actuating handle extending outwardly from the unit member in the direction of removal of such member, this handle being grasped and urged outwardly for both unlatching and removing the unit member from the frame member.

In accordance with an embodiment of the present invention, a plug-in unit is provided with rails at either side thereof for engaging matching rails in a main frame of an electronic apparatus or the like. A latching pin iS attached to one such member and is yieldably urged toward a locking position in the other member, `and speciiically towards a receiving location in the other member. Ramp means is also provided on the last mentioned member for initially engaging the latching pin as the plug-in unit is inserted in the frame. Thisvramp means deects the latching pin temporarily out of the way after which the latching pin becomes securely locked at a predetermined location. An unlatching plunger means is located for engaging the latching pin in its locked position. The plunger means is provided with further ramp means for urging the latching pin into an unlocked position when the plunger is operated. The plunger is 0perable from a knob or handle on the front panel of the plug-in unit and this handle is grasped in order to remove the plug-in unit from the frame. Thus, when the handle is grasped to remove the plug-in unit from the frame, the plug-in unit is unlatched and removed in one operation.

The subject matter which I regard as my invention is particularly pointed out and distinctly claimed in the concluding portion of this specification. The invention, however, both as to organization and method of operation, together with further advantages and objects thereof, may best 'be understood by reference to the following description taken in connection with the accompanying drawings in which:

FIG. 1 is a cross sectional view of a portion of a frame and plug-in yunit therefor, including a latching device in accordance with the present invention, and

FIG. 2 is a vertical cross section through the latching device in accordance with the present invention.

Referring to the drawings, a plug-in unit 10 is adapted to be received 4for operation within a main frame 12, which may comprise the housing for an electronic device. For example, the main frame 12 may be a portion of an instrument such as an oscilloscope with plug-in unit 10 comprising an interchangeable input amplifier or the like. When the plug-in unit is fully inserted into the main frame, electrical contact plug 14 connects circuitry of the plug-in unit to the instrument. In order to make accurate connection with the main frame, the plug-in unit is accurately guided in sliding engagement within the main frame and then locked into position. At this time plug 14 makes proper connection with socket 16. The plug-in unit 10 is securely locked in this position to prevent accidental separation between the plug-in unit and the main frame and provides general mechanical stability for the apparatuS.

The main frame 12 is provided with a rail 18 on either side of an opening in the main frame through which the plug-in unit 10 is received. The plug-in unit 10 also includes rails 19 positioned for accurate sliding engagement with rails 18 attached to the main frame. Rails 19 may take the form of slots extending the length of the plug-in unit 10 for accurately receiving rails 18. One such set of rails, 18-19, is provided on each side of the plug-in unit.

According to the present invention, an automatic latching mechanism secures plug-in unit 10 in its engaged position. This mechanism is located on one side of the plug-in unit and includes a latching means or pin 20 secured to plug-in unit 10 with rivets 22. The latching pin may conveniently take the form of a yieldable plastic member mounted within the plug-in unit 10 and having a normal position indicated at 20. In its normal position, the head of the pin protrudes through an aperture 23 in the plug-in units sidewall 24 and into the track of rail 18 between rails 19. The pin 20, may, however, be displaced outwardly from aperture 23 as indicated by dashed lines 26, as when plug-in unit 10 is inserted into frame 12. The plastic material of the pin'is stressed in the latter position so pin 20 provides its own restoring force urging the same 'back through aperture 23. Pin 20 has flat sides normally adjoining the edges of aperture 23 but the forwardmost protruding portion of the head is rounded.

One rail 18 includes a ramp portion 28 at the forward end thereof, facing the plug-in units pin 20, for the purpose of engaging and displacing the pin 20 when plug-in unit 10 is slid into the main frame. The forward end of this -rail 18 also contains a longitudinal cylindrical bore extending from the forwardmost end thereof to past the normal position of pin 20, with the plug-in unit fully engaged. Adjacent and rearward of ramp portion 28, and also facing plug-in unit 10, an indentation or aperture 32 extends through rail 18 into bore 30. In the fully engaged position of plug-in unit 10, pin 20 extends not only through aperture 23 in sidewall 24 but is also received through the aperture 32. When thus received, pin 20 fully locks the plug-in unit 10 in place. At this time, plug 14 fully connects with socket 16.

Bore 30 receives therewithin a cylindrical plunger 34 extending longitudinally into bore 30 from the plug-in unit when the plug-in unit is fully engaged. Plunger 34 has an enlarged head portion 36 having a diameter close to the inside diameter of `bore 30 and may be further provided with a tapering tip 38 assuring proper registration of plunger 34 with bore 30 when the two are slid together. Forward of enlarged head 36, plunger 34 has a substantially reduced cross section 40 at a position along the length thereof opposite the normal position of pin 20 with plug-in unit 10 in fully engaged position. In between enlarged head 36 and cross section 40, plunger 34 defines a ramp section 42 for displacing and unlocking pin 20 as hereinafter more fully described. In general, the contour of plunger 34 in the region of pin 20 is curved to match the curved abutting portion of pin 20 at the same location.

Plunger 20 is also provided with an actuating rod or handle 44 secured to plunger 34 on one end thereof and extending through an opening in the front panel 46 of plug-in unit 10. Handle 44 is slidable with respect to front panel 46 through such opening and is secured at the forward end thereof to pull knob 48. A coil spring 50 surrounds handle 44 between plunger 34 and the front panel.

This spring biases plunger 34 in a normal position such that cross section 40 is substantially adjacent the center of the head of pin 20. In this position, pull knob 48 will also abut front panel 46 of the plugin unit with the plunger thereby secured to the plug-in unit.

In operation, the plug-in unit 10 is initially positioned such that rails 19 engage rails 18 on the main frame and the plug-in unit is then inserted into the main frame. As pin 20 reaches the forward end of its adjacent rail 18, ramp portion 28 engages pin 20 and displaces the same to the position indicated by dashed lines 26. Then, as plugin unit 10 is urged further towards socket 16, pin 20 drops through aperture 32 in rail 18 and into bore 30 thereof adjacent small cross section 40 of plunger 34. At this time, plug 14 is fully engaged with socket 16. The plug-in unit 10 is now securely locked in position and cannot become accidentally separated from the main frame, pin 20 becoming a shear pin. Therefore, neither mechanical or electrical connection will be broken.

In order to remove plug-in unit 10, pull knob 48 is withdrawn forward from front panel 46 causing plunger 34 to move against the bias of coil spring 50. As plunger 34 thus moves forward, ramp section 42 engages the rounded head of pin 20 causing the same to be displaced towards the position illustrated in dashed lines at 26. When knob 48 is sufficiently extended, enlarged head 36 of plunger 34 will be opposite the center of the head of pin 20. At this time, pin 20 will not be displaced quite as far as the position indicated by dashed lines at 26, but will nevertheless be displaced to a position where its rounded head 52 can engage the edge of aperture 32 in rail 18. Pin 20 is then completely displaced to position 26 as the plug-in unit 10 is withdrawn. As the plug-in unit is withdrawn, rounded head 52 thus engages the edge of aperture 32 and then the side of rail 18.

An important feature and advantage of the present invention relates to the removal of plug-in unit 10. As pull knob 48 is withdrawn outwardly from front panel 46 of the plug-in unit, not only is the plunger 34 positioned to displace pin 20 for unlocking the plug-in unit, but also continued tension on the pull knob 48 withdraws the plugin unit from the frame. Thus the plug-in unit is unlatched and withdrawn in one motion. Similarly, the plug-in unit is inserted and locked in place by one inserting motion.

While a preferred embodiment according to the present invention is illustrated, it is apparent that variations can be made in the disclosed structure without departing from the invention. Thus, latching mechanisms can be located on each side of the plug-in unit which may be grasped by both hands in removal. Also, although the pin 20 is illustrated as being mounted upon the plug-in unit, this pin, yieldably urged toward the opposite relatively moving member, may alternatively be llocated upon the main frame.

It will be apparent to those skilled in the art that many other changes and modifications may be made. I therefore intend the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention.

I claim: 1. A latching device for securing an insertable unit member into a frame member comprising:

latching means mounted on one of said members yieldably urged toward the other of said memebrs in detent relation for engaging the same, the other of said members having a substantially matching vsurface forming an interlocking engagement with said latching means when said unit member is inserted in said frame member, and j an unlatching means mounted upon said unit member and engageable with said latching means to force the same out of engagement,

said unlatching means being provided with a movable actuating handle for operating said unlatching means, said handle extending outwardly from said unit member in the direction of removal of said unit member from said frame member, said handle providing the means for withdrawing said unit member from said frame member while unlatching the same by operation of said unlatching means in response to withdrawing movement of said handle.

2. A latching device for Ainterlocking a removable unit member with a frame member comprising:

rail means attached to said frame member,

rail means attached to said unit member slidable upon said iirst mentioned rail means as said unit member is inserted into said frame member,

pin means mounted upon said unit member yieldably urged towards said frame member for engaging 1the same in locking relation when said unit member is inserted into said frame member, and

plunger means slidably mounted on said unit member for disengaging said pin means from said frame member,

said plunger means having an operating handle accessible from the front of said unit memberfor operating said plunger to disengage said unit member from said frame member and for simultaneously withdrawing said unit member from said frame member.

3. A latching system for selectively latching a removable unit member in a frame member comprising:

first rail means attached to said frame member,

second rail means attached to said unit member and slidable along said rst rail means as said unit member is inserted into said frame member,

a locking means mounted on one of said members which is yieldably urged toward the remaining member for engagement therewith,

said remaining member having a ramp portion for engaging said locking means as said unit member and frame member are urged together such that said ramp portion displaces said locking means,

said remaining member being provided with an indentation adjacent said ramp portion for receiving said locking means in locking engagement when said unit member is further inserted in said frame member, and

plunger means having a ramp section for engaging said locking means when said unit member and said frame member are in locking engagement,

said plunger means having actuating means for moving said plunger in a direction causing said ramp section thereof to displace said locking means from said indentation so that said unit member is removable from said frame member.

4. A latching system for selectably latching a removable unit into a frame comprising:

first rail means attached to said frame,

second rail means attached to said unit and slidable along said first rail means as said unit is inserted into said frame,

a locking pin means mounted on said unit which is yieldably urged toward said rst rail means for engagement therewith,

said iirst rail means having a ramp portion for engaging said locking pin means as said unit and frame are urged together such -that said ramp portion displaces said locking pin means,

said first rail means being provided with an indentation adjacent said ramp portion for receiving said locking pin means in locking engagement when said unit is inserted in said frame, and

`a plunger mounted on said unit having a ramp section for engaging said locking pin means when said unit and said frame member are in locking engagement,

said plunger having an actuating handle accessible from the front of said unit for moving said plunger in a direction causing said ramp section thereof to displace said locking pin means from said indentation so that said unit is removable from said frame by l said actuating handle.

5. The system according to claim 4 wherein said plunger is provided with a spring normally spring biasing said plunger in a position retaining said locking pin means in a locked position within said indentation.

6. The system according to claim 4 wherein said rst rail means attached to said frame member includes a longitudinal bore in one end thereof for receiving said plunger longitudinally therein with said handle extending from said bore to said unit, said plunger and the handle thereof extending at least from said ramp portion of said first rail means to the indentation of said first rail means, said indentation comprising an aperture receiving said pin lmeans into the bore of said iirst rail means.

7. The system according to claim 6 wherein said plunger extends beyond said aperture when said unit member is fully engaged with said frame member, said plunger beyond said aperture including a portion of enlarged cross section and the portion of said plunger registering with said aperture having a smaller cross section for normally receiving said locking pin in a locked position thereof, the plunger between said enlarged portion and said smaller cross section providing the said ramp section of said plunger.

8. The system according to claim 4 wherein said locking pin means comprises a spring latch secured to an inside wall of said unit, said unit being provided with an aperture adjacent the rail means attached to said unit and through which said pin extends, said locking pin being formed of yieldable plastic.

9. A latching device for providing locking and unlocking of a unit member which is slidably insertable in a frame member, the unit member when inserted in the frame member having a panel accessible from outside the frame member, such latching device comprising:

latching means mounted on one of said members yieldably urged toward the other of said members for providing automatic locking between the unit member and the frame member when the unit member is inserted in such frame member, said latching means in locked position extending as a shear element in shear engagement with the other member, suchother member having an engageable surface completing the shear engagement with said latching means.

and unlatching means mounted on said unit member,

and having operating means accessible from said accessible panel of said unit member, said operating means being mounted for movement in the direction of removal of said unit member from said frame member, said unlatching means being engageable with said latching means and responsive to movement of said operating means to force said latching means out of said shear engagement when said operating means is grasped and moved outwardly for bringing about removal of said unit member from said frame member.

References Cited UNITED STATES PATENTS 628,322 7/1899 Hoffmire 312-333 X 1,092,651 4/1914 Jordan S12-333 I2,060,146 11/1936 Voorhees 312-333 X 2,789,024 4/ 1957 Heisler S12- 333 3,000,686 9/1961 Kobitter 312-333 3,140,905 7/1964 Trotter et al 312.-333 X JAMES T. MCCALL, Primary Examiner. 

